Route Every Prompt to the Cheapest Model: Building a Multi-LLM Cost Optimizer with Pydantic AI (opens in new tab)

The Problem: Every Prompt Costs Money, But Not Every Prompt Needs GPT-4 You're running an AI system in production. Some requests need Claude's reasoning depth. Others are simple classification tasks that Groq can handle in milliseconds for a fraction of the cost. The trap most teams fall into: they pick one model and stick with it. Here's the math that breaks you. Your engineering team sends a 50-token prompt asking "Is this email spam?" to GPT-4o. Cost: ~$0.015. Groq does the same thing for ...